1. Field of the Invention.
The present invention relates to earth excavating equipment for drilling large diameter holes in the earth, and more particularly to heavy-duty mobile devices of the kind sometimes described as downcrowdable telescopic augering apparatus or drilling rigs.
2. Description of the Prior Art.
A downcrowdable telescopic augering apparatus is disclosed in U.S. Pat. No. 4,877,091, which was issued to Richard L. Howell, Jr., on Oct. 31, 1989, and is incorporated herein by reference.
The configuration of the downcrowdable telescopic augering apparatus of Howell is not well adapted to downcrowdable telescopic augering apparatuses which are considerably larger in size and greater in power than the commercially sold apparatuses of Howell.
For example, the downcrowdable telescopic augering apparatus of Howell, if considerably scaled up, would be characterized by a higher than desirable center of gravity, because of its proportionately heavy kelly winch and winch drive motor, mounted at the top of the proportionately heavier kelly tube, which could cause severe stability problems when the vehicle carrying the apparatus was being moved over rough ground.
Further, the configuration of the Howell apparatus does not lend itself well to the incorporation of a service winch, which is highly desirable for carrying out common operations generally associated with the drilling of foundation holes, etc.
Yet further, the apparatus of Howell, if modified by relocating the kelly winch at the end of the boom without modifying the control system thereof, would unduly burden the operator with the necessity of constantly checking the kelly cable and manipulating the operator controls, so that the kelly cable would not become slack, leading to cable pileup on the kelly winch drum, which can result in reduced cable life.
The scaling up of the apparatus of Howell to provide taller and more powerful downcrowdable telescopic augering apparatuses would make it difficult or impossible for the operator to view the kelly winch, which the operator must do repeatedly during the operation of a downcrowdable telescopic augering apparatus.
The term "prior art" as used herein or in any statement made by or on behalf of applicant means only that any document or thing referred to as prior art bears, directly or inferentially, a date which is earlier than the effective filing date hereof.
No representation is made that a comprehensive search of the prior art has been made, or that no more pertinent information exists.
A copy of U.S. Pat. No. 4,877,091, issued to Richard L. Howell, Jr. on Oct. 31, 1989, and entitled AUGERING APPARATUS AND DRILLING RIG, is supplied to the United States Patent and Trademark Office herewith.